Warm weather, July rains bring an explosion of blood-sucking pests

They are relentless, wingless creatures that are reddish-brown in color and can jump nearly 30 times their height. They have specialized parts of their mouths that impale your skin, insert saliva to prevent blood coagulation and then tap your blood. They are nearly flat, their bodies polished and hard, which makes for easy movement through clothing, fur or feathers.

The flea has tormented humans and animals throughout history. They are the primary vector for spreading the plague. In the 14th century, the plague was known as the “Black Death” and killed an estimated 50 million people. So far this summer, two visitors have contracted the plague at Yosemite National Park, most likely through infected fleas.

Along the Central Coast, the number of fleas has significantly increased this year. In fact, veterinarian Susan Choy of Bear Valley Animal Clinic in Los Osos told me that they have seen about a 50 percent increase in fleas this month over years past. Numerous readers in the North County have written that they have never seen such a horrible year for flea infestations.

It’s believed that two main factors are contributing to the problem: the weather and the fleas' ability to adapt to flea control medications.

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Fleas flourish in warm and humid conditions. After a meal of blood, the females lay between 20 and 30 eggs a day. And the muggier it is, the faster the eggs will hatch. Not only will the eggs hatch quicker, but a greater number of larvae will successfully emerge.

The larvae are blind and, like a vampire, avoid sunlight. They lurk in dark places such as cracks and crevices. At this stage they are quite susceptible to lower humidity. In fact, they can actually dry out if relative humidity levels drop below 50 percent.

After about a week or two, the larva weaves a silken cocoon and becomes a pupa. There it waits for a signal — heat, carbon dioxide or vibrations — that a victim is near and emerges as an adult flea. Once it hatches, the flea’s only goal is to find blood and reproduce.

Here’s a scary statistic: Just 10 female fleas can multiply to more than a quarter of a million in their different life stages in just a month!

Unfortunately, our climate has become more to the fleas’ liking. This July was the hottest ever recorded in San Luis Obispo, with a mean temperature of 68.8 degrees, breaking the previous July record of 68.3 degrees, set just last year. Worldwide, this July was the hottest month on record, and 2015 will likely be warmer than 2014 — currently the warmest year on record.

The seawater temperatures along our coastline are at near-record levels, keeping overnight lows mild. Couple that with the record rains that we received in July — you might remember that Paso Robles received 3.5 inches of rain right before the start of the Mid-State Fair. Not only was it warm, but the relative humidity levels were more reminiscent of the Midwest. These are conditions fleas adore.

Another problem is that pet owners are utilizing older products to control fleas.

Unfortunately, the fleas have adapted to these medications, causing them to be ineffective. However, Dr. Choy told me that new treatments such as Comfortis can start to kill fleas within 30 minutes and last up to one month. It’s also FDA-approved.

Treatments like this will probably become more necessary as the long-range climate models predict a warmer climate and a greater occurrence of the North American monsoon for the Central Coast.

Climate change will continue to produce ominous consequences. For example, in the Aug. 16 edition of The Tribune there was an interesting article about ocean acidification caused by ever-higher concentrations of carbon dioxide in the atmosphere and oceans and its negative impacts on the oyster fisheries. And a warmer climate with higher humidity levels will allow pest such as fleas and ticks to thrive.

PG&E message: In the United States, the generation of electricity is one of the largest contributors of carbon dioxide. However, in PG&E’s service territory, the generation of electricity utilizing nuclear, solar, hydroelectric, wind, geothermal and biomass has made our state one of the cleanest in the country. In fact, more than 55 percent of the electricity that PG&E delivers to its customers is carbon-free. With each passing year, it’s expected to become cleaner.